Dark Matter: Galaxy Cluster Collisions Give New Principle Clues

New findings published in the journal Science went out to discover more about that large-scale structure of the universe that cannot simply be picked up with the naked eye. Researchers used two telescopes to work on better identifying these mysterious galatic ghosts, known more formally as dark matter.

"Dark matter is an enigma we have long sought to unravel," John Grunsfeld, assistant administrator of NASA's Science Mission Directorate, said in a news release. "With the combined capabilities of these great observatories, both in extended mission, we are ever closer to understanding this cosmic phenomenon."

With the help of two different microscopes, they sought out visible light in the universe with the Hubble Telescope and then X-rays with the Chandra Observatory. Though dark matter is invisible and does not interact with its surroundings, it is believed to actually make up 85 percent of the universe.

Of course, there are ways to better observe dark matter, including viewing another object through it. It's known to cause "gravitational lensing" by altering the light that travels through it.

Researchers found their work was successful in helping them better understand the properties of dark matter--something that is still being unraveled over time. When galaxy clusters run into one another, collisions stop or slow their progress. Yet researchers discovered with this research just how dark matter seems to be relatively unaffected by it.

"A previous study had seen similar behavior in the Bullet Cluster," Massey concluded. "But it's difficult to interpret what you're seeing if you have just one example. Each collision takes hundreds of millions of years, so in a human lifetime we only get to see one freeze-frame from a single camera angle. Now that we have studied so many more collisions, we can start to piece together the full movie and better understand what is going on."

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